Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 17: Elektronische Struktur (Experiment und Theorie) II

O 17.7: Vortrag

Dienstag, 9. März 2004, 12:45–13:00, H36

Electronic properties of a 2D-Superlattice of Ce Adatoms on Ag(111) — •M. Ternes1, C. Weber2, M. Pivetta1, F. Patthey1, J. Pelz3, T. Giamarchi4, F. Mila2, and W.-D. Schneider11Institut de Physique des Nanostructures, EPFL, CH-1015 Lausanne — 2Institut de Physique Théorique, EPFL, CH-1015 Lausanne — 3Departement of Physics, The Ohio State University, Columbus, Ohio 43210, USA — 4DPMC, Université de Genève, CH-1211 Genève

Recently we have shown that Ce adatoms on a clean Ag(111) surface form a hexagonal superlattice at liquid He temperatures [1]. This superlattice is created by long-range Ag(111) surface state mediated interactions between the Ce adatoms. We present here local STS measurements and spectroscopic images (dI/dV maps) taken at T=3.9 K on this superlattice showing site-dependent characteristic features very different from the clean Ag(111) surface. Calculations within a nearly free electron model and tight binding simulations show good agreement with our data. Furthermore, spectra obtained on compressed and slightly disordered lattices were successfully simulated and show the dependence of the LDOS on the local environment. Specifically, we identify the observed spectroscopic structures with singularities at the high-symmetry points of the mini-Brillouin zone created by the hexagonal Ce adatom superlattice. The stability of this superlattice results from the energy gain of the system manifesting itself by the opening of gaps at the mini-Brillouin zone boundery.

[1] F. Silly, M. Pivetta, M. Ternes, F. Patthey, J. Pelz, and W.-D. Schneider, Phys. Rev. Lett., in press.

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